Geminivirus vectors: From gene silencing to synthetic biology

Geminiviruses, the largest plant DNA virus family, cause devastating diseases in crops worldwide. These viruses possess distinctive features, such as the stem-loop structure and replication protein (Rep), which enable the creation of functional geminiviral replicons (GVRs) in plants. Over three decades, geminiviruses have been developed into vectors for virus-induced gene silencing (VIGS), high-level protein expression, and genome editing. This review introduces the genomic structure, Rep protein domains and functions, as well as the historical applications of geminiviruses, then highlights their prominent roles in VIGS and synthetic biology. As VIGS vectors, bipartite geminiviruses utilize AV1 gene replacement, while monopartite species rely on satellite DNAs to insert target sequences, enabling gene silencing in diverse plants. In synthetic biology, GVRs facilitate high-level protein expression through autonomous replication and enhance CRISPR/Cas genome editing efficiency in crops. Additionally, gene regulatory elements, including tissue-specific promoters and gene expression enhancement sequences from geminiviral genomes or satellite DNA expand their utility in genetic engineering. Finally, this review provides an outlook on the future development of geminivirus vectors. GVRs can work as plasmid-like DNAs for supporting diverse and creative designs in plant synthetic biology. The stem-loop structure and Rep are not unique to geminiviruses, a fact that suggests potential cross-kingdom applications of GVRs beyond plants. Vast viral resources enable further acceleration of GVR applications through resource mining and optimization. Moreover, attenuated or engineered geminiviral strains hold promise as "plant vaccines" via cross-protection. Collectively, geminivirus vectors bridge fundamental viral research with practical innovations in crop improvement, biomanufacturing, and synthetic biology.